1. Field of the Invention
The present invention relates to a complementary metal-oxide semiconductor (CMOS) radio frequency integrated circuit (RF IC), and more specifically, to a CMOS RF IC in which a DC bias circuit which is hardly affected by parasitic components is formed in a metal layer provided at the bottom of a metal layer in which an inductor is formed, while the size thereof is maintained.
2. Description of the Related Art
In general, an RF IC is referred to as a circuit in which an RF circuit is implemented on one semiconductor chip by using active and passive elements. The RF IC includes an amplifier, a transmitter/receiver, a synthesizer, and so on.
Further, CMOS is an element which is formed of silicon and has an excellent frequency characteristic in accordance with the development of micro-processing technology. Since the CMOS is based on silicon, chips can be manufactured at a low price by using a well-developed processing technique. Further, in the case of system-on-chip (SoC), even an intermediate frequency band of a system and a digital unit can be integrated.
An inductor is an essential element for implementing the CMOS technology in the RF IC. However, since an area occupied by the inductor in the IC is large at an RF band, there are difficulties in reducing the size of the chip.
Therefore, to reduce the chip size of the CMOS RF IC, a lot of studies have been conducted to reduce the size of the inductor. However, when the size is reduced, the performance of the CMOS RF IC may be degraded.